Longboye

"Dogs are better than human beings because they know but do not tell."

• Emily Dickinson

Longboye is a Haskell source prettifier.

Currently it only touches import statements but we plan to give the module statement and language pragmas a similar treatment as well adding as some whole-file touch-ups like hygenic whitespace management.

Pass the longboye imports command one or more paths to files or directories on the command line and it will prettify each file specified and each .hs file found recursively in each directory specified.

The Format

It's better seen than described, as in the next section ("Examples"), but the gist so far is:

• Any imports with a Prelude component are moved to the top.
• A blank line is added between any Prelude imports and the rest.
• Any extra blank lines between the first import and the top of the file are removed
• Any comments between the first import and the last import are removed
• Imports are sorted
• All imports are aligned in columns for qualified, the module name, as clause, and hiding clauses.
• Any imports with 0-1 members with 0-1 operators is left on the same line (eg. import Foo ( Bar( baz ) )).
• Any imports with 2 or more members or 2 or more operators are split across lines.
• A blank line is added between the last import and the rest of the file.
• Any extra blank lines between the last import and rest of the file are removed

Examples

For real examples of Goodboye™ format, see the Longboye source code (Longboye eats its own dog food):

• src/Longboye/ImportsParser.hs - a fairly typical example
• src/Longboye/Imports.hs - a file with a lot of imports and a hiding statement
• test/Spec.hs - a simple (mostly collapsed) file

It may take some developers a little time to get used to the exotic styling of the Goodboye™ format but those who have the fortitude to see it through will be rewarded with the bountiful gifts of clean code undreamed of by most of mankind.

Features

• Aligns all imports in normalized Goodboye™ format with patented insta-collapse
  • Sorts import statements
  • Sorts members within import statements
  • Removes duplicate import statements
  • Normalizes whitespace between module statement and import statements
  • Normalizes import statements and definitions
  • Normalizes whitespace between import statements and module body
  • Longboye will find and read .cabal files to load default extensions
• Emacs integration
• Is a good boy.
  • Yes he is.

Coming Soon

• #9 - Handle TypeNamespace and PatternNamespace
• #10 - Add -q option to prevent output other than errors
• #11 - Automatic removal of per-line trailing whitespace
• #12 - Automatic removal of per-file trailing whitespace
• #13 - modules sub-command for cleaning up module declarations
• #14 - pragmas sub-command for cleaning up LANGUAGE pragmas
• #15 - CLI combinators for imports / modules / pragmas commands.
• #5 - Better treatment of comments
• #6 - Better error handling in editor integration
• Possibly further bonus collapsing as/hiding/etc.

We love feedback, so feel free to chime in on any of the issues.

Caveats and Emptors^*

• Any comments that appear between the first uncommented import statement and the last uncommented import statement will be removed.

• Using the current emacs integration function will cause your cursor to jump around on save in some situations.

* Emptors are Functors over expectations.

Installation

$ make build install
...
$ longboye --help

Installation

$ make build install
$ longboye --help

Emacs Integration

Put something like this in the appropriate spot in your Emacs Init file. We suggest you use use-package and put it in the :init section of your haskell-mode package declaration.

  (defun longboyeee ()
    (interactive "r")
    (when (eq major-mode 'haskell-mode)
      (let ((start    1)
            (end      (+ 1 (buffer-size)))
            (program "longboye"))
        (let ((saved-cursor-position (point)))
            (call-process-region start
                                 end
                                 program
                                 t                   ;; delete
                                 t                   ;; destination
                                 nil                 ;; display
                                 "imports" "-")      ;; additional args
            (goto-char saved-cursor-position)))))

  (add-hook 'before-save-hook #'longboyeee)

See issue 20 for details of the issue of the cursor jumping around.

Data Integrity

The operations are performed by:

• making a temporary backup of the file in the same directory as the original
• writing the new content to a temporary file in the same directory
• atomically swapping the temporary file into place
• deleting the backup file

This should provide a relativel high degree of safety. If Longboye does detect an error it will abort all operations leaving the backup file in the same directory with a .longboye.bak extension.

License

Longboye is licensed under the BSD3 open source license. See LICENSE file.

Copyright Superpowers Corp © 2017.